The same four chords used in nearly every hit song which could be defined as "epic". Many people are fooled by the various transpositions, but its all the same stuff. The most popular progression of course being Em, C, G, D (just one example). Please note, the progression can start on any one of the chords, but it will include the other three invariably.
(First noted by a pair of absurdly innovative Oregon high school students).

Musically Uninformed Person:
"OMG! I love Owl City, they talk to my core being and are soooo origional!1!!!"

Musically Informed Person:
"You're a bitch slave to the music industry"

Record Executive:
"Well Jim, we found this new hot young singer who dresses really fuckin' weird like, so they're gonna love her, but she can't write music for shit!"
Co-Conspiring Producer:
"Well that's no problem! Just throw the epic chord progression at 'em with an edgy music video and they'll eat it right up!"